Gorm UUID foreign key - belongs to - go

Question

I'm trying to create a belongs to relation between two database tables, using GORM, my code is the following:
type Shop struct {
ID uuid.UUID `json:"id" gorm:"primaryKey;type:uuid"`
Name string `json:"name" gorm:"not null" validate:"required"`
City string `json:"city" gorm:"not null" validate:"required"`
State string `json:"state" gorm:"not null" validate:"required"`
}
type Employee struct {
ID uuid.UUID `json:"id" gorm:"primaryKey;type:uuid"`
FirstName string `json:"first_name" gorm:"not null" validate:"required"`
LastName string `json:"last_name" gorm:"not null" validate:"required"`
Email string `json:"email" gorm:"not null;unique" validate:"required,email"`
Password string `json:"password" gorm:"not null" validate:"required"`
Active bool `json:"active" gorm:"not null;default:false"`
ShopId uuid.UUID `json:"shop_id" gorm:"type:uuid"`
Shop Shop `gorm:"foreignKey:ShopID"`
}
When I run the migrations, this error pops up:
[error] invalid field found for struct .../.../.../api/models.Employee's field Shop: define a valid foreign key for relations or implement the Valuer/Scanner interface
I've found some references using number primary keys and they seem to work fine, but I can't find any solution to work with uuids...

Answer 1

I'm not sure, but what I understand of the message error is that the type uuid.UUID doesn't have implemented the methods for the interfaces Valuer and Scanner.
You should create your own type UUID, which can be something like this:
type UUID uuid.UUID
func(id UUID) Value() (driver.Value, error) {
return id.String(), nil
}
func (id *UUID) Scan(value interface{}) error {
dbID, ok := value.(string)
if !ok {
return errors.New("id scan: invalid value")
}
*e = uuid.MustParse(dbID)
return nil
}
And use it on your struct's definitions:
type Shop struct {
ID UUID `json:"id" gorm:"primaryKey;type:uuid"`
//...
}